Bilge pump problem

[Fisherman Rob]

I have a bilge pump connected behind a two battery switch. When on battery one or two, pump works fine, but on both the pump runs slowly, as if the battery is low. Both batteries read 12.4 to 12.6 volts. Any idea what could be wrong?

 

[uclueletcharters]

I'm no battery pro but I believe when selecting all your running your batteries in parallel which I believe changes the output you may want to research that as your pump is rated 12v and so many amp you don't want to burn it out by over powering it or lugging it. That's my stab in the dark lol.

 

[trophy fisher]

Sound like you have high resistance in the battery select switch when on ALL. Check for a voltage drop across the switch when the pump is running. TF

 

[Drewski Canuck]

If a Perko switch, and most are, then on battery one polarity is right, and on battery two polarity is right, then it cannot be set up as 24 volts. If so the pump would likely be burned out already. If polarity is wrong, the pump would spin backwards. The switch is not making a proper connection inside, which is usually because these switches really are not sealed, and the corrosion is shorting it out.

Try taking some alligator clip leads off battery one and two to set it up as parallel, not series, and see it the bypass to the pump changes things. If it works properly on the bypass, throw away the switch and start over.

Not the first corroded switch issue, and not a serviceable issue for the switch
Drewski

 

[Drewski Canuck]

If a Perko switch, and most are, then on battery one polarity is right, and on battery two polarity is right, then it cannot be set up as 24 volts. If so the pump would likely be burned out already. If polarity is wrong, the pump would spin backwards. The switch is not making a proper connection inside, which is usually because these switches really are not sealed, and the corrosion is shorting it out.

Try taking some alligator clip leads off battery one and two to set it up as parallel, not series, and see it the bypass to the pump changes things. If it works properly on the bypass, throw away the switch and start over.

Not the first corroded switch issue, and not a serviceable issue for the switch
Drewski

 

[tubber]

To my understanding, the only reason to ever run the boat on all/both is for emergency starting when both batteries get low. Have you tried to start the boat on all/both? Does it have enough juice to start if it can't run a bilge pump? Perhaps your bilge pump problem is really telling you that the Perko switch is pooched in the all/both position, as Drewski points out.

 

[wavetamer]

Normally the bilge is hooked directly to the positive of the battery so when the Main switch is off your bilge will still operate specially if it left in the water, . If your not getting proper voltage when in ALL, measure from the negative of your battery to the positive rail which feeds all of your boat, sounds like a bad connection in the back of your switch. You could try (with everything off) rapidly moving the switch back and forth specially in to the all position as it probably doesn't get there much, but I would pull the 4 screws and look in the back and insp connections, should be clean annually anyways , smear a little Vaseline to help prevent corrosion

 

[vanisland]

Bilge pumps should always be connected directly to one battery.

 

[Island Fish Lifter]

Bilge pumps should always be connected directly to one battery.

agreed. sounds like you have a voltage drop somewhere. I would find it first.